[kernel] Remove process & thread self-handles

For the coming switch to cap/handle ref-counting being the main lifetime
determiner of objects, get rid of self handles for threads and processes
to avoid circular references. Instead, passing 0 to syscalls expecting a
thread or process handle signifies "this process/thread".

src/kernel/objects/process.cpp

@@ -24,8 +24,6 @@ process::process() :
     kobject {kobject::type::process},
     m_state {state::running}
 {
-    m_self_handle = g_cap_table.create(this, process::self_caps);
-    add_handle(m_self_handle);
 }
 
 // The "kernel process"-only constructor
@@ -71,28 +69,6 @@ process::exit(int32_t code)
         current.exit();
 }
 
-void
-process::update()
-{
-    util::scoped_lock lock {m_threads_lock};
-
-    kassert(false, "process::update used!");
-    kassert(m_threads.count() > 0, "process::update with zero threads!");
-
-    size_t i = 0;
-    while (i < m_threads.count()) {
-        thread *th = m_threads[i];
-        if (th->has_state(thread::state::exited)) {
-            m_threads.remove_swap_at(i);
-            continue;
-        }
-        i++;
-    }
-
-    if (m_threads.count() == 0)
-        exit(-1);
-}
-
 thread *
 process::create_thread(uintptr_t rsp3, uint8_t priority)
 {

src/kernel/objects/process.h

@@ -20,9 +20,6 @@ public:
     /// Capabilities on a newly constructed process handle
     static constexpr j6_cap_t creation_caps = j6_cap_process_all;
 
-    /// Capabilities on a process to itself
-    static constexpr j6_cap_t self_caps = j6_cap_process_all;
-
     /// Top of memory area where thread stacks are allocated
     static constexpr uintptr_t stacks_top = 0x0000800000000000;
 
@@ -47,9 +44,6 @@ public:
     /// \arg code   The return code to exit with.
     void exit(int32_t code);
 
-    /// Update internal bookkeeping about threads.
-    void update();
-
     /// Get the process' virtual memory space
     vm_space & space() { return m_space; }
 
@@ -105,7 +99,6 @@ private:
     // This constructor is called by create_kernel_process
     process(page_table *kpml4);
 
-    j6_handle_t m_self_handle;
     int32_t m_return_code;
 
     vm_space m_space;

src/kernel/objects/thread.cpp

@@ -32,8 +32,6 @@ thread::thread(process &parent, uint8_t pri, uintptr_t rsp0) :
         m_tcb.rsp0 = rsp0;
 
     m_creator = current_cpu().thread;
-    m_self_handle = g_cap_table.create(this, thread::parent_caps);
-    parent.add_handle(m_self_handle);
 }
 
 thread::~thread()

src/kernel/objects/thread.h

@@ -57,9 +57,6 @@ public:
     /// Capabilities on a newly constructed thread handle
     static constexpr j6_cap_t creation_caps = j6_cap_thread_all;
 
-    /// Capabilities the parent process gets on new thread handles
-    static constexpr j6_cap_t parent_caps = j6_cap_thread_all;
-
     static constexpr kobject::type type = kobject::type::thread;
 
     enum class state : uint8_t {
@@ -168,9 +165,6 @@ public:
             uintptr_t rip0 = 0,
             uint64_t flags = 0);
 
-    /// Get the handle representing this thread to its process
-    j6_handle_t self_handle() const { return m_self_handle; }
-
     /// Create the kernel idle thread
     /// \arg kernel The process object that owns kernel tasks
     /// \arg rsp    The existing stack for the idle thread
@@ -208,7 +202,6 @@ private:
     message_data m_message_data;
 
     wait_queue m_join_queue;
-    j6_handle_t m_self_handle;
 };
 
 } // namespace obj